**2.3 Clinical manifestations of DR**

Fundus examination documents the presence and severity of retinal lesions. Clinical signs include:

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**2.4 Staging of DR**

(of 1 mm in diameter).

*Microvascular Complications of Diabetes Mellitus: Focus on Diabetic Retinopathy (DR)…*

ophthalmoscopy; they are best shown by fluorescein angiography

• **Microaneurysms:** tiny round red dots, typically located initially temporal to the fovea; sometimes hard to be differentiated from dot hemorrhages in

• **Retinal hemorrhages**: a) "dot-blot" hemorrhages result from the venous end of the capillaries and are located in the middle layer of the retina; b) "flameshaped" hemorrhages arise from pre-capillary arterioles and are located more

• **Retinal edema:** elevated, white-greyish appearance of the involved area; may be a consequence of leakage and fluid accumulation or of retinal ischemia (intracellular retinal edema). When foveal region is involved, it may assume a cystoid appearance and fluorescein angiography reveal a flower-petal pattern

• **Hard exudates:** these are well delineated, small, bright yellowish retinal lesions, formed by extravasated lipoproteins and lipid-filled macrophages and are mainly located in the outer plexiform layer. They are considered a sign of current or previous macular edema. When located in the macular region, they tend to organize in a circinate manner. They could resorb spontaneously months after the leakage is stopped, otherwise, chronic leakage leads to

• **"Cotton wool" spots**: these are small, whitish, fluffy superficial lesions, that cover the underlying retinal vessels and bear the significance of focal retinal ischemia and infarction. They are composed by neuronal debris and can disap-

• **Venous loops and venous beading (VB):** these frequently occur adjacent to areas of nonperfusion and bear the significance of increasing retinal ischemia

venous shunts, bypassing the capillary bed, and are considered an indicator of capillary occlusion and retinal ischemia. Together with VB, they are considered

• **Neovessels:** these are thin, with a single cell layer wall, extremely fragile, with a lace-like appearance and may be situated at the surface of the optic disk or elsewhere, in general at the periphery of the areas of non-perfusion. They can be best evidenced by fluorescein angiography and optical coherence tomography (OCT).

Dr is classically referred as: non-proliferative (NPDR) and proliferative (PDR).

The ICO guidelines also refer to the location, extension of the diabetic macular edema (DME), as it is an important cause of decreased vision in DR, even in the absence of neovessels. Central involved DME is considered to be an area of retinal thickening in the macula that does involve the central subfield zone

The classification is determined by the presence of retinal neovascularization. Recent Guidelines of International Council of Ophthalmology for Diabetic Eye Care recommends the following staging system, based on findings encountered in

ophthalmoscopy, to be used in clinical practice (**Table 1**).

• **Intraretinal microvascular abnormalities (IRMA):** these are arteriolo-

enlargement of the exudates and cholesterol accumulation.

the most significant predictor of progression to PDR [58].

*DOI: http://dx.doi.org/10.5772/intechopen.96548*

superficially in the retinal nerve fiber layer

pear in time by autolysis and phagocytosis.

*Microvascular Complications of Diabetes Mellitus: Focus on Diabetic Retinopathy (DR)… DOI: http://dx.doi.org/10.5772/intechopen.96548*

